Water heater tank



FIG. 1 is a front elevational view of the new water heater design;

FIG. 2 is a side elevational view of the water heater design, the side opposite being a mirror image thereof;

FIG. 3 is a rear elevational view of the water heater design;

FIG. 4 is a top plan view of the water heater design; and,

FIG. 5 is a bottom plan view of the water heater design.

The outermost broken lines immediately adjacent the stippled areas represent the bounds of the claimed design while all other broken lines are for illustrative purposes only; none of the broken lines form a part of the claimed design. 

The ornamental design for a water heater tank, as shown and described. 